Alfredo Aceves had a fantastic year last year. Unfortunately, his peripherals say he'll regress. A lot. But there is some reason to believe that Aceves can induce weak contact. With the data from baseball heatmaps.com, we can find batted ball distance for a hitter or off a pitcher.
Some people have found out that it does not matter how many line drives you hit, but how hard you hit them. The average line drive off Aceves went 233 feet. The average line drive Juan Pierre hit went 230 feet. Aceves is basically holding hitters to Juan Pierre's line drive distance. While Aceves' fly balls went 264 feet, and Pierre's went 247 feet, Pierre is a major outlier as Skip Schumacher, who no one would call a powerful hitter hit his average fly ball 262 feet. Someone like Matt Cain who has been famous for inducing weak contact had the average fly ball go 282 feet off him, and the average line drive go 242 feet. Mariano Rivera who's cutter jams hitters all the time and outperforms his peripherals every single year has his average line drive off him go 232 feet and fly balls go 268 feet. Very comparable to Aceves. From hittrackeronline.com, only one of the 8 homers Aceves gave up was a no doubter, and 2 of the homers he gave up were just enough home runs. Also from hittracker, the speed off bat of his homers was lower than league average.
While Aceves had a SIERA of 4.13 and an xFIP of 4.77, it definitely looks like he induced weak contact and maybe we could expect the same in 2012 from Aceves.